需求场景

获取网站点击的下载pdf，并把pdf重命名再上传到COS云上面

技术使用

“puppeteer”: “^19.7.2”,
“egg”: “^3.15.0”, // 服务期用egg搭的
文件服务使用COS腾讯云

核心思路

获取浏览器下载事件，并把文件保存到本地

const session = await substitutePage.target()       .createCDPSession();     await session.send('Page.setDownloadBehavior', {       behavior: 'allow',       downloadPath, // 指定文件保存路径回家     }); 

在保存到本地前监听此文件夹，如果有文件则获取并上传
加timer做防抖是为了防止在文件写入时以及重命名文件时多次触发watch函数，导致出会出现0KB源文件脏数据

 let timer: any = null;  fs.watch(downloadPath, async (_eventType, filename) => {  if (timer !== null) {  clearTimeout(timer);    }    timer = setTimeout(() => {      // 防止出现下载的临时文件就触发      if (filename.endsWith('.pdf')) {        resolve({          filename,        });      }    }, 500);  }); 

完整代码

    const session = await substitutePage.target()       .createCDPSession();     await session.send('Page.setDownloadBehavior', {       behavior: 'allow',       downloadPath, // 指定文件保存路径回家     });      // res就是文件相关信息了     const [ res ] = await this.downloadPdfHandler(substitutePage, downloadPath);     // filePath就是自己本地的文件所在绝对路径     const filePath = `${downloadPath}/${res.fileName}`;     // uploadFile是cos文件上传相关实现， 我就不放了，有私密的key     const pdfUriCode = await this.uploadFile(filePath, filePath);     const pdfUri = decodeURIComponent(pdfUriCode);     this.domainList = {       pdfSize: res.pdfSize,       pdfUri: pdfUri.substring(pdfUri.indexOf('root')),     }; 

downloadPdfHandler函数实现

  downloadPdfHandler(page, downloadPath): Promise {     const uuidName = uuidv4();     const fsWatchApi = () => {       // 使用防抖是为了防止下载的文件没有写入完全就重命名，那样会产生一个脏文件       let timer: any = null;       return new Promise<{ filename: string }>(resolve => {         fs.watch(downloadPath, async (_eventType, filename) => {           if (timer !== null) {             clearTimeout(timer);           }           timer = setTimeout(() => {             // 防止出现下载的临时文件就触发             if (filename.endsWith('.pdf')) {               resolve({                 filename,               });             }           }, 500);         });       });     };      function responseWatchApi() {       return new Promise(resolve => {         page.on('response', async response => {           // 检查响应是否为application/octet-stream且可能包含PDF（或你期望的其他文件类型）           if (response.headers()['content-type'].startsWith('application/octet-stream')) {             resolve();           }         });       });     }      return new Promise(async (resolve, reject) => {       try {          const [ , { filename }] = await Promise.all([ responseWatchApi(), fsWatchApi() ]);         const oldFilePath = path.join(downloadPath, filename);         const newFilePath = path.join(downloadPath, `${uuidName}.pdf`);         try {           fs.renameSync(oldFilePath, newFilePath);           this.logger.info(`文件名已经被修改完成:${uuidName}`);         } catch (error) {           this.logger.info(`文件名已经被修改完成:${uuidName}`);         }         await this.sleep(5 * 1000);         const files = fs.readdirSync(downloadPath);         // 创建一个数组，将文件名和其mtime（最后修改时间）一起存储         const filesWithMtime = files.map(file => {           const filePath = path.join(downloadPath, file);           const stats = fs.statSync(filePath);           return { fileName: file, mtime: stats.mtime, size: stats.size };         });         const newestFile = filesWithMtime.sort((a, b) => b.mtime.getTime() - a.mtime.getTime())[0];         this.logger.info('newestFile: %o', {           newestFile,         });         resolve({           pdfSize: newestFile.size,           fileName: newestFile.fileName,         });        } catch (e) {         reject(e);       }     });   }